The present invention relates to a gaming machine which includes plural video reels and is configured to execute a normal game and a free game shifted from the normal game.
Known gaming machines each having plural video reels employ the following technology, for example. According to the technology, when a trigger occurs, the video reels are upgraded for the free game which is developed from the normal game and about to start. After the video reels are upgraded, the player is able to easily achieve a winning combination (see, e.g., Patent Literature 1 (U.S. Patent Publication No. 2012/0172106)).